Diphenylpicrylhydrazyl (DPPH) spectrocolorimetery method was used to evaluate the anti-oxidative capacity of phytic acid,ascorbic acid (ASA),glutathione (GSH) and vegetable extracts.The results showed that eradication of free radical of phytic acid,ASA and GSH was pH dependent.The IC50 ,a value describing the ability of DPPH free radical scavenging,was 1.94 ×10-2(pH=2.0),0.26 (pH=4.6) and 1.86 (pH=5.7) for phytic acid,GSH and ASA,respectively.In addition,adding phytic acid enhanced the eradicating ability of free radical of vegetable extracts.The results suggested that phytic acid would be an important antioxidant in plants due to its high content in plants,and pose a crucial role in resistance to oxidative stress.